1. Field of Invention
The present disclosure relates to an active structure. More particularly, the present disclosure relates to a surface-enhanced Raman scattering (SERS)-active structure, a method for fabricating the SERS-active structure, and a SERS system comprising the SERS-active structure.
2. Description of Related Art
Surface-enhanced Raman scattering (SERS) is a technique concerning surface effects. The SERS technique is able to significantly enhance the Raman signal from analyte molecules, by such as adsorbed or adjacently jointed over a metal surface. In this regard, a structure is capable of enhancing the Raman signal of the analyte molecules over the metal surface is so called a SERS-active structure.
The SERS technique mainly applies the property of nanoscale metal materials which introduce local plasmonic field enhancement. In principle, the nanoscale metal materials, after being irradiated by a radiation source, have a surface plasmon resonance with the radiation and exhibit aggregation and oscillation of electrons at localized spot, so as to generate a strong plasmonic field in a near field. In general, the position of the strong plasmonic field is known as hot spots.
Compared to traditional Raman scattering, the SERS technique is better at trace measurement and surface specificity, such that it has broader applications. However, both occurrence of surface effects and the enhancement of Raman signal are strongly affected by the surface structure of the metals where analyte molecules adsorbed or are adjacent to. This is why a SERS-active structure itself and a fabrication method thereof play such a crucial role in the SERS technique.
With the conventional SERS-active structure, the generated hot spots have drawbacks narrow scope and unconcentrated distribution. Conventional fabrication methods for the SERS-active structures such as electron beam lithography and focused ion beam milling are at high cost but low yield because of the requirements of complicated steps and expensive apparatus.